The trio and Egypt cut diplomatic and economic ties with Qatar on June 5, imposing an air, land and marine blockade on the country, accusing it of ties to Iran and "extremist groups" as well as interference in their internal affairs.

Qatar denies the claims and accuses the four countries of an attack on its sovereignty.

Trump chose Saudi Arabia for his first overseas visit as president in May, two weeks before the Gulf crisis erupted.

Qatar is meanwhile home to a huge US airbase, where the forward headquarters of Centcom - the regional command which leads operations against the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group - is based.